The present invention relates to an arrangement in an automatic winding machine for winding and unwinding a cable, thread or other similar product on and from a flanged drum, respectively. The winding machine typically includes:
two gripping pins positioned in a support frame vertically displaceably and arranged to coaxially grip one flange of the drum, respectively, and to lift the drum from a floor plane; PA0 a power means for displacing the gripping pins vertically between a fixed upper winding position and a lower gripping position varying in accordance with the diameter of the flange of the drum; PA0 a rotation apparatus supported by the support frame and comprising a displaceable drive wheel and a press means for pressing the drive wheel against the flange of the drum; and PA0 an adjusting means for displacing the drive wheel to an operating position against the flange of the drum. PA0 that the winding machine is provided with a means for detecting a vertical distance of one gripping pin from the floor plane in the position for gripping the drum to determine the diameter of the flange of the drum; and PA0 that the detecting means is arranged to influence, on the basis of the detected distance, both the adjusting means of the drive wheel to adjust the drive wheel to an operating position corresponding to the diameter of the flange of the drum, and the press means of the rotation apparatus to regulate the pressing of the drive wheel against the flange of the drum with a force corresponding to the diameter of the drum flange.
A winding machine of this type is used especially in the cable industry for winding a cable on a drum or for unwinding a cable from a drum, but it is equally applicable for winding other similar products, such as threads and ropes. The winding machine operates in such a manner that the drum is gripped by means of the gripping pins of the winding machine and lifted up from the floor plane to a fixed winding position, whereafter the drum is rotated by means of a rotation apparatus which is pressed against one flange of the drum. One embodiment of this kind of winding machine is disclosed in the U.S. application Ser. No. 07/778,124 and U.S. Pat. No. 4,781,335.
Winding drums used in such winding machines vary in size, that is, their flanges differ in diameter. Therefore it is necessary that the rotation apparatus be displaceable by adjusting means to an appropriate operating position in which the drive wheels of the rotation apparatus contact the periphery of one flange of the drum.
Moreover, winding drums used in such winding machines are made of different materials, such as metal, plastic and wood, wherefore it is necessary that the pressure by which the drive wheel of the rotation apparatus is pressed against the flange of the drum be adjustable to an appropriate value. Large drums normally require a high pressure on account of the thick cable to be wound, whereas small drums normally require a low pressure. An excessive pressure exposes the drive wheel to wear, while an inadequate pressure causes slippage as well as wear. Maximum pressure causes a risk that the drive wheel will break the drum, especially small drums with flanges made of a weaker material.
In prior art winding machines of this type, the drive wheel of the rotation apparatus is adjusted manually to an appropriate distance from the fixed winding position of the gripping pins, or the winding position of the gripping pins is adjusted to an appropriate distance from the fixed operating position of the drive wheel. In both cases, the adjustment is merely approximate, since the accuracy of adjustment is totally dependent on the professional skill and experience of the operator making the adjustments. Prior art winding machines have a single preset pressure value, as a result of which the drive wheel wears down too rapidly, and the drum is liable to damage. Even in cases where manual adjustment of the pressure is possible, the accuracy of adjustment is nevertheless totally dependent on the professional skill and experience of the operator.